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James Clerk
Maxwell (13 June 1831 to 5 November 1879) was a Scottish mathematical physicist,
born in Edinburgh. Maxwell developed a set of equations expressing the basic laws
of electricity and magnetism as well as the Maxwell distribution in the kinetic
theory of gases. He was the last representative of a younger branch of the well-known
Scottish family of Clerk of Penicuik.
Maxwell had perhaps the finest mathematical
mind of any theoretical physicist of his time. Maxwell is widely regarded as the
nineteenth century scientist who had the greatest influence on twentieth century
physics, making contributions to the fundamental models of nature. In 1931, on
the centennial anniversary of Maxwell's birthday, Einstein described Maxwell's
work as the "most profound and the most fruitful that physics has experienced
since the time of Newton."
Algebraic mathematics with elements of geometry
are a feature of much of Maxwell's work. Maxwell demonstrated that electric and
magnetic forces are two complementary aspects of electromagnetism. He showed that
electric and magnetic fields travel through space, in the form of waves, at a
constant velocity of 3.0 × 108 m/s. He also proposed
that light was a form of electromagnetic radiation.
Biography
Early
years
Maxwell was born at 14 India Street, Edinburgh, Scotland. He was
the only child of Edinburgh lawyer John Clerk. Maxwell's early education was provided
by his Christian mother and included studying the Bible. Most of his early childhood
was spent at the family estate Glenlair near Dumfries. Maxwell's mother died when
he was just eight years old. Maxwell then went to Edinburgh Academy in his youth.
His school nickname was "Daftie", earned when he arrived for his first
day of school wearing home-made shoes. In 1845, at the age of 14, Maxwell wrote
a paper describing mechanical means of drawing mathematical curves with a piece
of twine.
Middle
years
In 1847, Maxwell
attended the University of Edinburgh studying natural philosophy, moral philosophy,
and mental philosophy. At Edinburgh, he studied under Sir William Hamilton, 9th
Baronet. In his eighteenth year, while still a student in Edinburgh, he contributed
two papers to the Transactions of the Royal Society of Edinburgh — one
of which, On the Equilibrium of Elastic Solids, laid the foundation of
one of the most singular discoveries of his later life, the temporary double refraction
produced in viscous liquids by shear stress. In 1850, Maxwell left for Cambridge
University and initially attended Peterhouse, but eventually left for Trinity
College where he believed it was easier to obtain a fellowship. At Trinity, he
was elected to a secret society known as the Cambridge Apostles. In November 1851,
Maxwell studied under the tutor William Hopkins (nicknamed the "wrangler maker").
A considerable part of the translation of his electromagnetism equations was accomplished
during Maxwell's career as an undergraduate in Trinity.
In 1854, Maxwell
graduated with a degree as second wrangler in mathematics from Trinity (scoring
second-highest in the mathematics exam) and was declared equal with the senior
wrangler of his year in the higher ordeal of the Smith's prize examination. For
more than half of his relatively short life he held a prominent position in the
foremost rank of scientists, usually as a college professor. Immediately after
taking his degree, he read to the Cambridge Philosophical Society a novel memoir,
On the Transformation of Surfaces by Bending. This is one of the few purely
mathematical papers he published, and it exhibited at once to experts the full
genius of its author. About the same time his elaborate memoir, On Faraday's
Lines of Force appeared, in which he gave the first indication of some of
the electrical investigations which culminated in the greatest work of his life.
From
1855 to 1872, he published at intervals a series of valuable investigations connected
with the Perception of Colour and Colour-Blindness, for the earlier
of which he received the Rumford medal from the Royal Society in 1860. The instruments
which he devised for these investigations were simple and convenient. In 1856,
Maxwell was appointed to the chair of Natural Philosophy in Marischal College,
Aberdeen, which he held until the fusion of the two colleges there in 1860.
In
1859 he won the Adams prize in Cambridge for an original essay, On the Stability
of Saturn's Rings, in which he concluded the rings could not be completely
solid or fluid. Maxwell demonstrated stability could ensue only if the rings consisted
of numerous small solid particles. He also mathematically disproved the nebular
hypothesis (which stated that solar system formed through the progressive condensation
of a purely gaseous nebula), forcing the theory to account for additional portions
of small solid particles.
In 1860, he was a professor at King's College
London. In 1861, Maxwell was elected to the Royal Society. He researched elastic
solids and pure geometry during this time.
Kinetic
theory
One of Maxwell's greatest investigations was on the kinetic theory
of gases. Originating with Daniel Bernoulli, this theory was advanced by the successive
labours of John Herapath, John James Waterston, James Joule, and particularly
Rudolf Clausius, to such an extent as to put its general accuracy beyond a doubt;
but it received enormous development from Maxwell, who in this field appeared
as an experimenter (on the laws of gaseous friction) as well as a mathematician.
In
1865, Maxwell moved to the estate he inherited from his father in Glenlair, Kirkcudbrightshire,
Scotland. In 1868 he resigned his Chair of Physics and Astronomy at King's College,
London.
In 1866, he statistically formulated, independently of Ludwig Boltzmann,
the Maxwell-Boltzmann kinetic theory of gases. His formula, called the Maxwell
distribution, gives the fraction of gas molecules moving at a specified velocity
at any given temperature. In the kinetic theory, temperatures and heat involve
only molecular movement. This approach generalized the previous laws of thermodynamics,
explaining the observations and experiments in a better way. Maxwell's work on
thermodynamics led him to devise the thought experiment that came to be known
as Maxwell's demon.
Electromagnetism
The
greatest work of Maxwell's life was devoted to electricity. Maxwell's most important
contribution was the extension and mathematical formulation of earlier work on
electricity and magnetism by Michael Faraday, André-Marie Ampère, and others
into a linked set of differential equations (originally, 20 equations in 20 variables,
later re-expressed in quaternion and vector-based notations). These equations,
which are now collectively known as Maxwell's equations (or occasionally, "Maxwell's
Wonderful Equations"), were first presented to the Royal Society in 1864, and
together describe the behaviour of both the electric and magnetic fields, as well
as their interactions with matter.
Furthermore, Maxwell showed that the
equations predict waves of oscillating electric and magnetic fields that travel
through empty space at a speed that could be predicted from simple electrical
experiments—using the data available at the time, Maxwell obtained a velocity
of 310,740,000 m/s. Maxwell (1865) wrote:
- This velocity is so nearly
that of light, that it seems we have strong reason to conclude that light itself
(including radiant heat, and other radiations if any) is an electromagnetic disturbance
in the form of waves propagated through the electromagnetic field according to
electromagnetic laws.
Maxwell proved correct, and his quantitative
connection between light and electromagnetism is considered one of the great triumphs
of 19th century physics.
At that time, Maxwell believed that the propagation
of light required a medium for the waves, dubbed the luminiferous aether. Over
time, the existence of such a medium, permeating all space and yet apparently
undetectable by mechanical means, proved more and more difficult to reconcile
with experiments such as the Michelson-Morley experiment. Moreover, it seemed
to require an absolute frame of reference in which the equations were valid, with
the distasteful result that the equations changed form for a moving observer.
These difficulties inspired Einstein to formulate the theory of special relativity,
and in the process Einstein abandoned the requirement of a luminiferous aether.
Later
years and afterwards
Maxwell
also made contributions to the area of optics and colour vision, being credited
with the discovery that colour photographs could be formed using red, green, and
blue filters. He had the photographer Thomas Sutton photograph a tartan ribbon
three times, each time with a different colour filter over the lens. The three
images were developed and then projected onto a screen with three different projectors,
each equipped with the same colour filter used to take its image. When brought
into focus, the three images formed a full colour image. The three photographic
plates now reside in a small museum at 14 India Street, Edinburgh, the house where
Maxwell was born.
Maxwell's work on colour blindness won him the Rumford
Medal by the Royal Society of London. He wrote an admirable textbook of the Theory
of Heat (1871), and an excellent elementary treatise on Matter and Motion
(1876). Maxwell also was the first to explicitly use dimensional analysis, also
in 1871.
In 1871, he was the first Cavendish Professor of Physics at Cambridge.
Maxwell was put in charge of the development of the Cavendish Laboratory. He supervised
every step of the progress of the building and of the purchase of the very valuable
collection of apparatus paid for by its generous founder, the 7th Duke of Devonshire
(chancellor of the university, and one of its most distinguished alumni). One
of Maxwell's last great contributions to science was the editing (with copious
original notes) of the Electrical Researches of Henry Cavendish, from which it
appeared that Cavendish researched such questions as the mean density of the earth
and the composition of water, among other things.
Maxwell married Katherine
Mary Dewar when he was 27 years of age, but the had no children. He died in Cambridge
of abdominal cancer at the age of 48. He had been a devout Christian his entire
life.
The extended biography The Life of James Clerk Maxwell, by
his former schoolfellow and lifelong friend Professor Lewis Campbell, was published
in 1882 and his collected works, including the series of articles on the properties
of matter, such as Atom, Attraction, Capillary Action, Diffusion,
Ether, etc., were issued in two volumes by the Cambridge University Press
in 1890.
Poetry
and song
As a great lover of British poetry, Maxwell memorized poems and
wrote his own. The best known is Rigid Body Sings closely based on Comin'
Through the Rye by Robert Burns, which he apparently used to sing while accompanying
himself on a guitar. It has the immortal opening lines[1]:
- Gin a body
meet a body Flyin' through the air.
- Gin a body hit a body, Will it fly? And
where?
A collection of his poems was published by his friend Lewis
Campbell in 1882.
Legacy
The
scientific compound derived CGS unit measuring magnetic flux (commonly abbreviated
as f), the maxwell (Mx), is named in his honour. A mountain range on Venus,
Maxwell Montes, is named after him. It is the only feature on Venus that is named
for a male (all others are given female names). The James Clerk Maxwell Building
(built in 1977) at the University of Edinburgh and the James Clerk Maxwell Telescope
are also named after him. The latter is the largest sub-mm astronomical telescope
in the world, with a diameter of 15 metres. He also has a building named after
him in King's College London at the Waterloo campus in commemoration of him being
Professor of Natural Philosophy at King's from 1860 to 1865. At the University,
he also has a chair in Physics named after him and a society for undergraduate
physicists.
Publications
- Maxwell, James Clerk, "On the Description of Oval Curves, and those having
a plurality of Foci". Proceedings of the Royal Society of Edinburgh, Vol.
ii. 1846.
- Maxwell, James Clerk, "Illustrations of the Dynamical Theory
of Gases". 1860.
- Maxwell, James Clerk, "On Physical Lines of Force".
1861.
- Maxwell, James Clerk, "A Dynamical Theory of the Electromagnetic
Field". 1865.
- Maxwell, James Clerk, "Theory of Heat". 1871.
- Maxwell,
James Clerk, "A Treatise on Electricity and Magnetism". Clarendon Press,
Oxford. 1873.
- Maxwell, James Clerk, "Molecules". Nature, September,
1873.
- Maxwell, James Clerk, "Matter and Motion", 1876.
- Maxwell,
James Clerk, "On the Results of Bernoulli's Theory of Gases as Applied to their
Internal Friction, their Diffusion, and their Conductivity for Heat".
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